91213121 has 4 divisors (see below), whose sum is σ = 91263744. Its totient is φ = 91162500.

The previous prime is 91213097. The next prime is 91213123. The reversal of 91213121 is 12131219.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 91213121 - 2¹⁰ = 91212097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91213093 and 91213102.

It is not an unprimeable number, because it can be changed into a prime (91213123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22505 + ... + 26246.

It is an arithmetic number, because the mean of its divisors is an integer number (22815936).

Almost surely, 2^91213121 is an apocalyptic number.

It is an amenable number.

91213121 is a deficient number, since it is larger than the sum of its proper divisors (50623).

91213121 is a wasteful number, since it uses less digits than its factorization.

91213121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50622.

The product of its digits is 108, while the sum is 20.

The square root of 91213121 is about 9550.5560571100. The cubic root of 91213121 is about 450.1450084114.

The spelling of 91213121 in words is "ninety-one million, two hundred thirteen thousand, one hundred twenty-one".